Have you ever wondered if there’s a natural way to lower your high blood pressure, guard against Alzheimer's, lose weight, and feel better? Well as it turns out there is. Michael Greger, M.D. FACLM, founder of NutritionFacts.org, and author of the instant New York Times bestseller “How Not to Die” celebrates evidence-based nutrition to add years to our life and life to our years.

Do You Need to Be Gluten-Free?

A lot of people have gluten-free diets, but is it for you?

This episode features audio from The Potential Harm in Unnecessary Gluten-Free Diets, Is Gluten Sensitivity Real?, and Gluten-Free Diets: Separating the Wheat from the Chat. Visit the video pages for all sources and doctor’s notes related to this podcast.


We have a lot of choices to make about our diet. Add to that – doing the right thing when it comes to treating a chronic illness, fighting a virus, or losing weight, and suddenly, our nutrition choices can seem almost overwhelming.  

Well, I’m here to help. Welcome to the Nutrition Facts podcast. I’m your host – Dr. Michael Greger.

More than 10,000 articles have been published on gluten in medical journals—intimidating even for me! Today, we have a three-part series – summarizing the best available science on gluten.

In our first story, we look at how we might prevent the inflammation that occurs from gluten-free diets.

Over the last decade or so, there’s been a growing interest in the medical literature on plant-based eating, beyond just exclusionary terms like vegetarian or vegan. Previous such studies were somewhat limited because they just split people up into either vegetarian or nonvegetarian, excluding some or all animal foods––but without taking into account the quality of plant foods. Vegans could be living off of French fries, Oreos, and Coca-Cola. Enter: “Changes in Plant-Based Diet Quality and Total and Cause-Specific Mortality,” the first study to investigate the associations between changes in plant-based diet quality and subsequent risk of death. 

If you look at overall plant-based diet scores, the more you increase your intake of any plant foods and decrease your intake of any animal foods, the lower your risk of death appears to fall, but that’s because people were adding healthy plant foods like fruits and vegetables. If you just look at people who ate more processed, sugary junk over time, their mortality risk goes up, the clinical implications being that increasing intake of healthy plant foods and decreasing intake of not just animal foods, but also animal crackers, could lower the future risk of premature death. Whereas just reducing the intake of carbs in general, cutting down not just refined carbs and sugars, but healthy high-carb foods like fruits and whole grains, is associated with increased overall mortality––which would correspond to years of your life being cut short, as well as the risk of dying specifically from heart disease, stroke, and cancer.

Why are whole plant foods so good for us? Much of the benefit may be mediated by our microbiome. There are all sorts of things threatening our good gut bugs, like the over-prescription of antibiotics. However, the only factor that has been empirically shown to be important is a diet low in microbiota-accessible carbohydrates––in other words, prebiotics like fiber and resistant starch, only found one place in abundance: whole plant foods. We went from high-MAC diets to Big Mac diets, and may be suffering the consequences.

Intake of dietary fiber, which is the main source of MACs in the diet, is negligibly low compared to how we evolved. Such a low-fiber diet provides insufficient food for our gut microbes, starving ourselves of all the wonderful things they produce for us. A low-fiber diet is a key driver of microbiome depletion, and this loss is implicated in the rampant increase of chronic diseases that now plague the modern world.

We evolved getting perhaps a hundred grams of fiber a day. Our gut bugs must have been in heaven. How do you get even close to that? A cup of fruit may only have about three grams, a cup of vegetables, five grams. Why so little? Because fruits and vegetables are like 80 to 90 percent water. One has to go to the drier plant foods to really scale it up––like beans, at 15 grams, or intact grains like barley, over 30 grams per cup. But many people are avoiding common grains these days, like wheat barley and rye, due to gluten. But there is a dark side of gluten-free diets.

Now, if you have a condition like celiac disease, then you absolutely have to avoid gluten, but if not, the downsides include the potential for nutritional deficiencies, like not getting enough fiber, and toxic compounds, for example, the accumulation of heavy metals in people on gluten-free diets. Those following a gluten-free diet had significantly increased blood mercury levels––more arsenic flowing through their systems. The arsenic is likely due to increased rice consumption, because rice is a major ingredient in gluten-free foods. But you can certainly choose other grains, like sorghum—that’s my favorite rice substitute. And the higher mercury may just be because people eating gluten-free diets were tending to eat more fish for some reason. But the reason that 10 out of 10 of those without celiac disease or a recognized gluten sensitivity following a gluten-free diet experienced a pro-inflammatory gastrointestinal environment is likely due to starving your microbial self, not getting enough prebiotics, not getting enough fiber because you’re avoiding grains like wheat; so, whatever diet you choose for whatever reason, make sure you’re getting enough fiber.

In our next story, we look at how the effects of gluten on our health have been debated for more than 30 years.

In 1980, researchers in England reported a series of women who suffered from chronic diarrhea that resolved on a gluten-free diet, yet did not have evidence of celiac disease, the autoimmune disorder associated with gluten intolerance. The medical profession was skeptical at the time, and even 30 years later, so much so, that much like patients who had irritable bowel syndrome, patients claiming non-celiac gluten sensitivity were commonly referred to psychiatrists because they were believed to have an underlying mental illness. Psychological testing of such patients, however, found no evidence that they were suffering from some psychosomatic hysteria.

The medical profession has a history of dismissing diseases as all in people’s heads—PTSD, ulcerative colitis, migraines, ulcers, asthma, Parkinson’s, MS. Despite resistance from the prevailing medical community each time, however, these health problems have subsequently been confirmed to be credible physiologically-based disorders rather than psychologically-based confabulations.

On the flipside, the internet is rife with unsubstantiated claims about gluten-free diets, which has spilled over into the popular press to make gluten the diet villain du jour, with claims like “17 million Americans are gluten sensitive.” However, it must be remembered that this is also “big business.”

When literally billions are at stake it’s hard to trust anybody; so, as always, best to stick to the science. What sort of evidence do we have for the existence of a condition presumed to be so widespread?

Not much. The evidence base for such claims was unfortunately very thin because we didn’t have randomized controlled trials demonstrating that the entity even exists. The gold standard for confirming non-celiac gluten sensitivity requires a gluten-free diet, followed by a double-blind, randomized, placebo-controlled food challenge. Like you give someone a muffin, and they’re not told if it’s gluten-free or gluten-filled—to control for placebo effects—and see what happens. The reason this is necessary is because when you actually do this, a number of quote-unquote “gluten-sensitive” patients don’t react at all to disguised gluten and instead react to the gluten-free placebo. So, it truly was “in their heads.”

But we never had that level of evidence until…2011, when a double-blind, randomized placebo-controlled trial was published, which tested to see if patients complaining of irritable bowel type symptoms who claimed they felt better on a gluten-free diet—despite not having celiac disease—actually could tell if they were given gluten-containing bread and muffins or gluten-free bread and muffins.

They started out gluten-free and symptom-free for two weeks and then they were challenged with the bread and muffins. Here’s what happened to the 15 patients who got the placebo, meaning they started out on a gluten-free diet and continued on a gluten–free diet. They got worse. Just the thought that they may be eating something that was bad for them made them feel crampy and bloated. This is what’s called the nocebo effect. The placebo effect is when you give someone something useless and they feel better; the nocebo effect is when you give someone something harmless and they feel worse. But the small group that got the actual gluten, felt worse still. So, they concluded, this non-celiac gluten intolerance may actually exist.

It was a small study, though, and even though they claimed the gluten-free bread and muffins were indistinguishable, maybe at some level the patients could tell which is which. So, in 2012, researchers in Italy took 920 patients that had been diagnosed with non-celiac gluten sensitivity and put them to the test with a double-blinded wheat challenge by giving them not bread and muffins but capsules filled with wheat flour or filled with placebo flour, or a kind of placebo powder, no flour at all. And more than two-thirds failed the test, like they got worse on the placebo or better on the wheat. But of those that passed, there was a clear benefit to staying on the wheat-free diet, confirming the existence of a non-celiac wheat sensitivity. Note, they said wheat sensitivity, not gluten sensitivity.

Gluten itself may not be causing gut symptoms at all. See, most people with wheat sensitivity have a variety of other food sensitivities. Two-thirds are sensitive to cow’s milk protein as well; then, eggs were the most common culprit.

So, if you put people on a diet low in common triggers of irritable bowel symptoms and then challenge them with gluten, there’s no effect. Same increase in symptoms with high gluten, low gluten, or no gluten, calling into question the very existence of non-celiac gluten sensitivity.

Interestingly, despite being informed that avoiding gluten wasn’t apparently doing a thing for their gut symptoms, many participants opted to continue following a gluten-free diet as they subjectively described “feeling better;” so, the researchers wondered if avoiding gluten might be improve the mood of those with wheat sensitivity and indeed, short-term exposure to gluten appeared to induce feelings of depression in these patients. But whether non-celiac gluten sensitivity is a disease of the mind or the gut, it is no longer a condition that can be dismissed.

Finally today, how common is gluten sensitivity? Are there benefits to gluten? Why does the medical profession explicitly advise against people who suspect they might be gluten intolerant just going on a gluten-free diet? Let’s find out.

Until only a few years ago, almost the whole of the scientific world maintained that the wheat protein gluten would provoke negative effects only in people with rare conditions such as celiac disease or wheat allergies, but by the early part of 2013, it was largely becoming accepted that some nonceliac patients could suffer from gluten or wheat sensitivity.

And, indeed, a consensus panel of experts now officially recognizes three gluten-related conditions: wheat allergy, celiac disease, and gluten sensitivity. So, what percentage of the population should avoid wheat?

About 1 in a thousand may have a wheat allergy, nearly 1 in a 100 have celiac disease, and it appears to be on the rise, though there’s still less than about a 1 in 10,000 chance Americans will get diagnosed with celiac in a given year. How common is wheat sensitivity? Our best estimate at this point is in that same general range, slightly higher than 1%, but still that’s potentially millions of people who may have been suffering for years who could have been cured by simple dietary means, yet were unrecognized and unhelped by the medical profession.

Although gluten sensitivity continues to gain medical credibility, we still don’t know how it works, or how much gluten can be tolerated, if it’s reversible or not, and what the long-term complications might be of not sticking to the diet. Considering the lack of knowledge, maybe people with gluten sensitivity should try reintroducing gluten back into their diet every year to see if it’s still causing problems.

The reason health professionals don’t want to see people on gluten-free diets unless absolutely necessary is that for the 98% of people that don’t have gluten issues, whole grains—including the gluten grains wheat, barley, and rye—are health promoting, linked to the reduced risk of coronary heart disease, cancer, diabetes, obesity, and other chronic diseases.

Just like because some people have a peanut allergy, doesn’t mean everyone should avoid peanuts. There is no evidence to suggest that following a gluten-free diet has any significant benefits in the general population. Indeed, there is some evidence to suggest that a gluten-free diet may adversely affect gut health in those without celiac disease or gluten sensitivity or allergy. They’re talking about this study that found that a month on a gluten-free diet may hurt our gut flora and immune function, potentially setting those on gluten-free diets up for an overgrowth of harmful bacteria in their intestines. Why? Because, ironically, of the beneficial effects of the very components wheat sensitive people have problems with—like the FODMAP fructans that act as prebiotics and feed our good bacteria, or the gluten itself, which may boost immune function. Less than a week of added gluten protein significantly increases natural killer cell activity, which could be expected to improve our body’s ability to fight cancer and viral infections. High-gluten bread improves triglyceride levels better than regular gluten bread, as another example.

Ironically, one of the greatest threats gluten-free diets pose, may be the gluten itself. Self-prescription of gluten-free diet may undermine the ability to pick up celiac disease, the much more serious form of gluten intolerance. The way we diagnose celiac is by looking for the inflammation caused by gluten in celiac sufferers, but if they haven’t been eating a lot of gluten, we might miss the disease.

Hence, rather than being on a gluten-free diet, we want celiac suspects to be on a gluten-loaded diet. We’re talkin’ 4-6 slices of gluten-packed bread every day for at least a month so we can definitively diagnose the disease. Why does it matter to get a formal diagnosis if you’re already on a gluten-free diet? Well it’s a genetic disease; so, you’ll know to test the family, but most importantly many people on gluten-free diets are not actually on gluten-free diets. Even 20 parts per million can be toxic to someone with celiac. Many on so-called gluten-free diets inadvertently still eat gluten. Sometimes there’s contamination of gluten-free products; so, even foods labeled quote-unquote gluten-free may still not be safe for celiac sufferers. That’s why we need to know.

The irony, editorialized in a prominent medical journal, of many celiac patients not knowing their diagnosis, while millions of non-sufferers banish gluten from their diets, can be considered a public health farce.

We would love it if you could share with us your stories about reinventing your health through evidence-based nutrition. Go to nutrition facts.org slash testimonials. We may share it on our social media to help inspire others.

To see any graphs, charts, graphics, other images, or studies mentioned here, please go to the NutritionFacts podcast landing page. There you’ll find all the detailed information you need – plus links to all of the sources we cite for each of these topics.

For a vital, timely text on the pathogens that cause pandemics, you can order the E-book, audio book, or the hard copy of my latest book “How to Survive a Pandemic.” Or, go to your local public library, for that matter.

For recipes, check out my new “How Not to Diet Cookbook.” It’s beautifully designed, with more than 100 recipes for delicious and nutritious meals. And, of course, all proceeds I receive from the sales of my books go to charity.

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